3D printing is the term used for a process of making a three-dimensional solid object by the laying down of successive layers of an extrudable and settable material from a moving dispenser. The first examples of apparatus performing a process meeting this description were produced in the nineteen eighties.
An example of such an apparatus is described in European patent number EP0833237. This describes an apparatus which incorporates a movable dispensing head provided with a supply of material which solidifies at a predetermined temperature, and a base member, which are moved relative to each other along “X”, “Y,” and “Z” axes in a predetermined pattern to create three-dimensional objects by building up material discharged from the dispensing head onto the base member at a controlled rate. The apparatus is preferably computer driven. Three-dimensional objects may be produced by depositing repeated layers of solidifying material until the shape is formed.
In recent years the costs of 3D printers have fallen substantially so that the range of applications for which they are useful has greatly increased. The technology is now much more accessible, with more commercially available devices. Many hobbyists have also built their own 3D printers of various designs.
A typical 3D printer comprises a moving head into which a plastic filament, typically about 3 mm in diameter, is fed. This passes over a heating mechanism and is forced through a nozzle which is formed, for example, of a metal or metal alloy such as brass. The nozzle comprises a circular aperture, for example of 0.35 mm diameter which deposits a thread of up to 1 mm diameter. Such apparatus is usually computer controlled. Computer software executing on the computer typically translates a digital design into the required head movements to build up a three-dimensional object by successive thread deposition.
The material used in 3D printers as described above typically comprises one or more plastics materials, typically thermoplastics, and particularly acrylonitrile butadiene styrene (ABS). Other thermoplastics which have been used successfully include nylon, polystyrene and polylactic acid (PLA).
A problem with the method of deposition described above is that the surfaces of articles produced show imperfections as a result of the method of deposition. For example, where a plastics material such as ABS is used, a ridged pattern on the surface results from the successive deposition of individual filaments onto a previously set filament layer. It would be advantageous to provide a method for mitigating these effects.